1. Field of the Invention
The invention relates in general to a substrate structure and a package structure using the same, and more particularly to a substrate structure having metal tiles for increasing structural strength and a package structure using the same.
2. Description of the Related Art
The two opposite surfaces of the substrate structure normally have different proportions in metal structure. For example, one surface of the substrate structure has a number of traces, and the opposite surface has a number of connecting pads connected to a number of conductive solder balls. As the two opposite surfaces of the substrate structure may differ widely in terms of the proportions of traces and connecting pads, the proportions of the metal structure of the two opposite surfaces also differ widely. Further due to the difference in the coefficient of thermal expansion and in the metal structure, the substrate structure operating in a high temperature will generate stress and become warped. Such deformation may damage the substrate structure. For example, elements on the substrate structure such as traces, conductive solder balls and chips may break, crack, or come off.
An ordinary practice to reduce the deformation is achieved by adding a metal mesh layer such as a copper mesh layer on the two opposite surfaces of the substrate structure, so that the proportions of the metal structure between the two opposite surfaces of the substrate structure become closer to each other. Referring to FIG. 1, a conventional substrate structure is shown. A surface 102 of the substrate structure 100 has a number of traces 110 and a number of metal mesh layers 104. The opposite surface (not illustrated) of the substrate structure 100 also has a number of metal mesh layers. With the disposition of the metal mesh layers, the proportions of the metal structure in the two opposite surfaces of the substrate structure become closer to each other and the deformation is reduced accordingly.
Referring to FIG. 2, the manufacturing of a metal mesh layer of FIG. 1 is shown. The shading region 112 of the mask 106 corresponds to the metal mesh wires 124 of the metal mesh layers 104 of FIG. 1. The metal mesh wire 124 is adjacent to the trace 110. The transparent region 108 corresponds to the hollowed portions 114 of the metal mesh layers 104 of FIG. 1. After portions of the photo-resist layer 116 of the substrate 120 is exposed by the light L passed through the mask 106, the portions of the exposed photo-resist is removed through subsequent developing process. Then, in the subsequent etching process, the metal mesh layers 104 and the traces 110 are formed on the metal layer 122 by way of etching.
As indicated in FIG. 2, in order to make the mask 106 flat, during the exposing process, the mask 106 is pulled to the two ends in two opposite directions D1 and D2, and the mask 106 is thus extended, making the transparent region 108 and 118 become wider along the directions D1 and D2. The widths of the transparent region 108 and 118 make the light L1 passing through the transparent region 108 and 118 diffracted wider. Thus, the interval S1 between the traces 110 and the metal mesh wire 124 adjacent thereto becomes wider due to the extension of the mask and the expansion of scattered light. As the interval S1 becomes wider, the distribution range of the metal mesh layer 104 becomes smaller accordingly, and the control of the proportions of the metal structure between the two opposite surfaces of the substrate structure becomes more difficult.